Stories in Spanish: Costa Rica becomes the first Central American country to confirm swine flu (“gripe porcina”). A 21 year old who had traveled to Mexico is in stable condition. An additional 16 cases were examined but were negative. Brazil is also examining 11 travelers; cases are also being examined in Panama, Honduras, Argentina, and Uruguay, and Chile.

Most of the cases that are being examined have traveled to Mexico recently, but secondary spread may be occurring in New York City. 45 cases have been confirmed to date, but many more are suspected or have been alluded to in news reports. This extended human-to-human chain of transmission is the worrisome part–if this is efficient, it’s going to be much more difficult to get ahead of the virus and minimize spread. Expect much focus in the coming days and weeks to be on contacts of infected cases, in an effort to determine the frequency of secondary transmission…

I am vainly searching for information on the Mexican cases. How many had direct animal contact? I read elsewhere that there was no swine flu epidemic in pigs in Mexico. If so where did this suddenly come from?

Also why is the transmission risk person to person so different. Clearly most cases are transmitted this way, but there seems to be a major difference not only in virulence but in transmissability of the Mexican subtype in contrast to the “identical subtype” isolated in US/other cases.

No idea. I was listening to the B.C. patient talking about how many people she interacted with in Canada, coughing etc, before she was diagnosed & none of them have caught it. Health officials here seem to think it’s not spreading human-to-human easily.

It has been reported that this new virus isolated from a swine flu patient contains some genetic material belonging to the swine fever virus which attacks pigs. At some time in the past, the swine fever virus in pigs must have gained entry into humans in close and repeated contact without producing any disease. This provides the opportunity for the virus to adapt to the human environment and then mutates to produce a disease in man that is transmissible to another human. Since human beings do not have the immunity against this new disease, therefore it tends to be very serious and sometimes fatal.

However, regarding person to person transmission, a host of other factors like the exposure dose (of virus), and the biological variation between individuals play a role too. So, not everyone in contact will get the disease, and of those who do, it will appear in various forms of severity.

It is kind of worrying… there’s roughly, what? 7 Billion people in the world and the mortality is around 1% at the moment so that means 70 million people will die worldwide of swine flu. That’s 700,000 in the UK and 3 million in the US alone which is a lot of people! There’s a very up to date outbreak map tracker and news links on http://www.flutrack.info, seems to be updated several times a day.

Claire, you’re making the assumption that everyone will contract the H1N1 virus. That is highly unlikely.
Your estimate of near 1% case mortality is higher than most. Figures I’ve seen are less than one half of one percent.